The present invention relates to a cassette tray for radiography to be attached inside an image receiving section on an X-ray direct photographing table, and more particularly, the invention relates to a mechanism for positioning an X-ray film cassette tray.
X-ray diagnostic radiography or X-ray photographing has been carried out mostly on a direct radiography or X-ray photographing table. As a typical direct radiography table, there is a standing-type radiography table. In this radiography table, a column of a stand is provided with an X-ray image receiving section, and the X-ray image receiving section moves up and down along guide rails disposed on both side walls of the column so that an X-ray image is directly recorded on a film.
FIGS. 6(a) and 6(b) show a cassette tray attached to the aforementioned radiography table. In order to take radiograph or X-ray photograph, a cassette 9 is held at right and left sides thereof by holding plates 8 disposed at both sides of a tray 2, and a lower part of the cassette 9 is supported by a spacer 10 having a size corresponding to a size of the cassette. As described above, the cassette 9 is set in the tray 2 and is disposed on the radiography table to take radiograph.
As cassettes without side grooves used for general radiography, seven kinds of the cassettes having the following sizes are standardized in JIS-Z4905 according to IEC (International Electrotechnical Commission) standard, wherein the sizes of these seven cassettes are as follows: 388 mm.times.464 mm (for a half-cut size, JK14.times.17); 388 mm.times.388 mm (for a large square size, JK14.times.14); 313 mm.times.388 mm (for a continental size, JK11.times.14); 286 mm.times.337 mm (for a quarter-cut size, JK10.times.12); 235 mm.times.286 mm (for sixth-cut size, JK8.times.10); 198 mm.times.248 mm (for eighth-cut size, JK61/2.times.81/2); and 153 mm.times.198 mm (for a cabinet size, JK41/2.times.61/2). Therefore, in order to precisely attach the various-sized cassettes 9 at a central upper position of the cassette tray 2, it is necessary to prepare five kinds of the spacers 10 having different heights.
The conventional cassette tray for general photographing is structured as described above. In order to securely attach the various-sized cassettes 9 to the central upper position of the tray 2, it is necessary to set the spacer 10 corresponding to the size of the cassette, and to move the holding plates 8 at both sides of the tray 2 to both sides of the cassette 9 for holding the same securely. However, in this case, there are problems that the size of the spacer 10 prepared during an operation may be selected incorrectly, and the spacer 10 might be dropped on a floor while being set.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a cassette tray for radiography wherein various-sized cassettes can be securely held at a central upper position of a tray to be held inside an image receiving section of a direct X-ray photographing table.
Another object of the invention is to provide a cassette tray 2 as stated above, wherein an operation for setting the cassette can be easily carried out in a short period of time.
Further objects and advantages of the invention will be apparent from the following description of the invention.